1. Field of the Invention
The present invention concerns a local coil for magnetic resonance applications, with an annular carrier or base body in which a reception antenna is embedded to receive a magnetic resonance signal.
2. Description of the Prior Art
Local coils of the above type are generally known. They are used in order to achieve a better magnetic resonance exposure from specific regions of an examination subject (normally a person) than is possible with a whole-body coil. Thus, for example, head, arm, leg and other local coils are known.
In the case of diseases of human tissue in the region of the base of the skull, for example pituitary tumors or inflammatory diseases of the eye organs, today head coils are used as a rule for examination. The head coils serve, depending on the design, either only to receive the magnetic resonance signal or both to excite and to receive the magnetic resonance signal.
The head of the patient fills such a head coil well. This coil shape is therefore well suited for an overall image of the head. Also, with such a head coil a significantly better image of the head can be generated in comparison with a whole-body coil. When a detail exposure of the base of the skull is needed, however, in individual cases the signal quality is unsatisfactory, particularly with regard to the signal-to-noise ratio and the measurement time required for the acquisition of the magnetic resonance signals.
A local coil for magnetic resonance applications is known from PCT Application WO 01/09632 that has an annular base body in which a reception antenna is embedded to receive a magnetic resonance signal. In this local coil, the base body is fashioned with inherent stability, such that it assumes an inherent form when not subjected to deforming forces. However, it is dimensioned and flexibly fashioned such that it can be inserted via a body opening of a person into the corresponding body cavity of the person and removed again from it. Within the body cavity of the person, the base body thereby assumes its inherent form.
According to PCT Application WO 01/09632, as a rule the local coil is inserted via an operative incision into the person in the body cavity of the person, for example the patient""s abdominal cavity. It is moved by means of a rigid guide rod connected to the base body, however, guiding and positioning of the base body by means of a catheter is also noted.
A local coil for magnetic resonance applications is known from PCT Application 93/05706 that has a base body in which a reception antenna is embedded to receive a magnetic resonance signal. The base body is dimensioned and flexibly fashioned such that it can be rectally inserted into the bowel of a person and removed again therefrom.
A local coil for magnetic resonance applications is known from German OS 43 37 908 in which a pre-intensifier is arranged separate from a base body of the local coil.
An object of the present invention is to provide an improved local coil, with which diagnostic imaging of higher quality is possible in the region of the base of the skull.
The object is achieved in accordance with the invention by an MR local coil having a base with inherent stability, such that a state with no deforming forces acting thereon assumes an inherent form, with the base body being dimensioned such that it substantially assumes its inherent form given arrangement in the palate and/or in the nasal cavity of a person, and the base body is flexible, such that it can be inserted via a nostril into the nasal cavity and removed again from it.
The base body preferably is connected with an elastic supplementary body. The stability of the local coil can thereby be increased.
In the simplest embodiment, the supplementary body is simply provided and cannot be changed. Preferably, however, it has a connection with which it can be filled (inflated) with a gaseous or liquid medium. The local coil then can be placed more precisely at the base of the skull.
When the supplementary body is arranged on one side adjacent to the base body, the location of the local coil can be defined even more precisely.
When a pre-intensifier is arranged following (in the signal propagation direction) to the reception antenna, the signal-to-noise ratio can be improved even further.
The pre-intensifier alternatively can be integrated into the base body or be connected with the base body via a cable. When, in the latter case, the cable exhibits a length between 8 and 20 cm, the pre-intensifier can be arranged outside of the human body while the base body is inside the body, namely in the region of the palate or the nasal cavity.